Railway-traffic-controlling apparatus



July 16, 1929. A A; H SON 1.720.866

RAILQVAY TRAFFIC CONTROLLING APPARATUS Filed Sept. 192,8 2 Sheets-Sheet1 OR, H. 5'. Thompson,

H ATTORNEY July 16, 1929. H. A. THOMPSON 1.720.866

V RAILWAY TRAFFIC CONTROLLING APPARATUS I I Filed Set. 1s, 192e 2Sheets-Sheet 2 V ENTOR H, FLT/wornpsah M ATTORNEY Patented July 16,1929.

UNETED STATES.

PATENT OFFICE.

HOWARD A. THOMPSON, OF EDGEWOOD BOROUGH, PENNSYLVANIA, A$SIGNOR TO THEUNION SWITCH & SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A

(1031 03 ATION OF PENNSYLVANIA.

RAILWAYTRAFFIG-CONTROLLING APPARATUS.

Application filed September 13, 1928. Serial No. 305,757. 9

My invention relates to railway traffic controlling apparatus, andparticularly to automatic signaling apparatus of the type involvinglight signals. I

I will describe two forms of railway traf fic controlling apparatusembodying my 1nvent-ion and will then point out the novel featuresthereof in claims.

In the accompanying drawing, Fig. 1 is a diagrammatic view illustratingone form of railway traffic controlling apparatus embodying myinvention. Fig. 2 is a similar view showing a modified form of theapparatus illustrated in Fig. 1, and also embodying my invention.

Similar reference characters refer to similar parts in both views.

Referring first to Fig. 1, the reference characters 1 and 1 designatethe track rails of a stretch of railway track over which trafficnormally moves in the direction 111- dicated by the arrow. These trackrails are divided, by means of insulated joints 2, into a plurality ofsuccessive track sections BC, (1 D, etc. Each such track section 18provided with a track circuit comprising a source of current located theexit end of the section, and a track relay located at the entrance endof the section. As here shown, the source of current for each trackcircuit is a track transformer designated by the reference character Ewith an exponent corresponding to the location, and having its secondary3 connected across the rails. The primary 4 of each transformer E isconstantly connected with the terminals X and Z of a suitable source ofalternating current not shown in the drawing. The track relay for eachtrack section is designated by the reference character F with anexponent corresponding to the location, and comprises a track winding 5which is constantly con nected with the rails, and a local winding 6which is at times supplied with alternating current in a manner whichwill be described hereinafter.

Each track section is provided with a line transformer designated by thereference character K with an exponent corresponding to the location,and comprising a primary 18 which is constantly supplied withalternating current from an alternator L over line wires 49 and 50, anda secondary 17 which is divided into three sections 17 and 17 Each tracksection is also provided with a line relay designated by the referencecharacter H with an exponent corresponding with the location. Each linerelay H comprises a local winding 9, a reverse control winding 7, anormal control winding 8, and four contacts 12, 13, 14, and each capableof being moved into a left-hand or reverse position, a vertical ormiddle position, and a right-hand or normal position. Referringparticularly to line relay H the winding 9 of this relay is constantlysupplied with alternating current from the terminals X and Z. Thewinding 7 of this relay is also constantly supplied with alternatingcurrent over a circuit which passes from section 17 of secondary 17 ofline transformer K through Wires 19 and 20, winding 7 of line relay Hand wires elO and 21 back to section 17". Winding 8 of relay H isprovided with three circuits. The first circuit for this winding passesfrom section 17 of secondary 17 of line transformer K through wires 19and 23, winding 8 of relay H front contact 24; of track relay F wire 25,back contact 26 of track relay F and wire back to section 179 ofsecondary 17 of line transformer K l V hen this first circuit is closed,the current which flows in winding 8 of relay H is of the same relativepolarity as the current flowing in winding 7, and this current flowingin winding 8 therefore aids the effect of the current flowing in winding7 Under these conditions relayH is energized in the reverse direction.The magnitude of this current in winding 8 is such that if winding 7should become open-circuited for any reason when this first circuit isclosed, relay H would still be energized in the reverse direction. Thesecond circuit for winding 8 of relay H passes from section 17 ofsecondary 17 ofline transformer K, through wires 19 and 28, windingS ofrelay H front contact 24 of track relay F wire 25, front contact 26 oftrack relay F wire 27, reverse contact 15 of line relay H and wire 28back to section 17 b of secondary 17 of line transformer K hen thissecond circuitis closed, the current which flows in winding 8 of relay Hhas approximately thesame magnitude as the current flowing in winding 7of this relay,

but is of the opposite relative polarity, so I that this current inwinding 8 neutralizes the effect of the current in winding 7, and relayH therefore closes its middle contacts. The third circuit for winding 8of relay H passes from section 17 b of secondary 17 of line transformerK in series through wires 19 and 23, winding 8 of relay H, front contact2 1 of track relay F wire 25, front contact 26 of track relay F wire 27,and thence through middle contact 15 of line relay H and wire 29 back tosection 17 of secondary 17 of line transformer K or through normalcontact 15 of line relay H and wires 30 and 29 back to sections 17 ofsecondary 17 of line transformer K When this third circuit for winding 8of relay H is closed, current from both windings 17 and 17 oftransformer K flows in winding 8, and this current is of approximatelytwice the magnitude of the current flowing in winding 7, and is of theopposite relative polarity from the current flowing in winding 7, sothat this current in winding 8 opposes and exceeds the effect of thecurrent in winding 7 and relay H therefore closes its normal contacts.If all of the circuits for winding 8 are open, the contacts of relay Hare swung to their reverse positions under the influence of windings 9and 7 The circuits for the remaining line relays are similar to thecircuits ust traced for line.

relay H", and will be readily understood from the drawing.

The supply of current to the winding 6 of each track relay is controlledby the reverse contact 12 of the associated line relay and by the frontcontact 16 of the track relay itself. Referring particularly to trackrelay F, for example, when reverse contact 12 of line re lay H is closedcurrent is supplied to winding 6 of relay 1 over a pickup circuit whichpasses from terminal X through reverse contact 12 of line relay H, wires31 and 32, and winding 6 of relay F to terminal hen relay F is closed,however, current is then supplied to winding over stick circuit whichpasses from terminal K through frontcontact 16 of track relay F wire 32,and winding 6 of relay F to terminal Z.

Locate-d adjacent the entranre end of each track section is a traclstwaysignal here shown as a light signal having an upper group of lamps 11,and a lower group of lamps 10. The upper group of lamps 11 comprises agreen lamp G, a first yellow lamp Y a second yellow lamp Y and a redlamp R; and the lower roup of lamps comprises a green lamp G and a redlamp R When both red lamps in signal are lighted, the signal indicatesstop; when the second yellow lamp Y of the upper group and the red lampR of the lower group are both lightec the signal indicates approach;when the first yellow lamp Y of the upper group and the green lamp G ofthe lower group are both lighted, the signal incicates approachrestricting; and when the green lamp G of the upper group and the redlamp R of the lower group are both lighted, the signal indicatesproceed.

As shown in the drawing, a train indicated diagrammatically at Woccupies the section immediately to the right of point D so that trackrelay F is tie-energized. All circuits for winding 8 of line relay H aretherefore open at front contact 2 1 of track relay F and the contacts ofline relay H occupy their reverse positions. A stop indication circuitfor signal J is closed at back contact 33 of track relay F and currentflows from section 17" of secondary 17 of line transformer K throughwires 19, 39, and 38, red lamp R of the lower group, wires 37 and 36,red lamp R of the upper group, wire 35, back contact 33 of track relay F,,and wires 3t and 21 back to section 17. The red lamp R of the uppergroup, and the red lamp R of the lower group are therefore both lighted,so that signal J indicates stop. Section CD is unoccupied, so trackrelay F is energized. The first circuit for winding 8 of line relay H istherefore closed at front contact 24: of track relay F and at backcontact 26 of track relay F and the contact of relay H occupy theirreverse positions. An approach indication circuit for signal J istherefore closed at front contact 33 of track relay F and at reversecontact 13 of line relay H and current flows from section 17 ofsecondary 17 of line transformer K through wires 19, 39, and 38, redlamp R of the lower group, wires 37 and d3, the yellow lamp Y of theupper group, wire 42, reverse contact 13 of line relay H wires 56 ands1, front contact 33 of track relay l and wires 34 and 21 back tosecondar 17'. The yellow lamp Y of the upper group and the red lamp R ofthe lower group are therefore lighted, and signal J indicates approach.In section BG, track relay F is energized and the second circuit forwinding 8 of line relay H is therefore closed at front contact 2 1 oftrack relay F and at reverse contact of line relay H so the contacts ofrelay H occupy their middle positions. An approach restrictingindication circuit for signal J is closed at front contact 33 of trackrelay F and at middle contact 14- of line relay H and current flows fromsection 17 of secondary 17 of line transformer K through wires 19, 39,and 47, green lamp G of the lower group, wire 16, yellow lamp Y of theupper group, wire 45, middle contact 14: of line relay H wire 53 and 41,front contact 33 of track relay F and wires 3% and 21 back to'section 17of secondary 17. The yellow lamp Y of the upper group and the green lampG of the lower group are therefore lighted, so that signal J indicatesapproach restricting. Track relay F at point A is energized, and thethird circuit for winding 8 of relay H is therefore closed, so

that the contacts of relay H occupy their normal positions. A proceedindication circuit for signal J A is therefore closed at front contact33 of track relay F and normal contact 15 of line relay H and currentflows from section 17? of secondary 17 of line transformer K throughwires '19, 39, and 38, red lamp R of the lower group, wire 37, greenlamp G of the upper group, wire 48, normal contact 14 of line relay Hwires 53 and 41, front contact- 33 of track relay F and wires 34 and 21back to section 17" of secondary 17 of line transformer K. The greenlamp G of the upper group and the red lamp R of the lower group aretherefore lighted so that sig nal J indicates proceed.

It will be noted that since the pick-up circuit for each track relayincludes a reverse. contact 12 of the associated line relay, if, for anyreason, the line relay fails to become energized in the reversedirection while the corresponding section is occupied by a train, thenwhen the train leaves the section, the pick-up circuit for the trackrelay will remain open, and the track relay will fail to becomeenergized. As a result, the signal for the corresponding section willremain at stop, and the failure of the line relay would be detected. Forexample, I will assume that winding 7 or winding 8 of line relay H ,-orboth, become o )en-circuited, and that a train enters section A-B. Whenthe train enters the section, track relay F becomes de-energized,thereby opening its stick circuit at its front contact 16, and alsoopening all three circuits for winding 8 of line relay H at frontcontact 24 of track relay F Since a winding of line relay H is now opencircuited, this relay becomes de-energized, and the reverse contacts ofthe relay do not close. When the train passes out of section AB, thepick-up circuit for track relay F is open at reverse contact 12 of linerelay H so track relay F does not pick up. Signal J therefore remains atstop after the train has passed out of section AB, and the failure'ofline relay H will then be detected.

In the modified form of apparatus shown in Fig. 2, the detailedarrangement of the approach restricting and proceed indication circuitsfor each signal has been modified so that the energy for the approachrestricting and proceed indications of each signal J is supplied by theline transformer for the section next in advance. Referring to signal Jfor example, the approach restricting indication circuit for this signalpasses from section 17 of secondary 17 of line transformer K throughWire 28, reverse contact 15 of line relay H wire 27, front contact 26 oftrack relay F wire 25, front contact 24 of track relay F wire 44, middlecontact 14 of line relay H wire 45, yellow light Y of the upper group ofsignal J wire 46, green lamp G of the lower group, wires 47, 39, 19

and 54, line Wire 49, and wire 54, back to section 17 of secondary 17 ofline trans? former K The proceed indication circuit for signal J passesfrom sections 17 and 17 b of secondary 17 of line transformer K, throughwire 29, middle contact 15 of line relay H 3, wire 27, front contact 26of track relay F wire 25, front contact 24 of track relay F wire 44,normal contact 14 of line relay H wire 52, resistor 51, wire 48, greenlamp G of the upper group of signal J wire 37, red lamp R of thelowergroup, wires 38, 39, 19 and 54 line wire 49, and Wire 54 backtosections 17 a and 17 b of secondary 17 of line transformer K Thiscircuit is also provided with a branch which passes from wire 29 throughwire 30 and normal contact 15 of line relay H to wire 27. In otherrespects the apparatus is similar to that shown in Fig. 1, except thatthe circuit for winding 8 of each relay H, which includes a frontcontact of the associated track relay and a back contact of the linerelay next in advance is omitted. The circuits for the remaining signalsare similar to the circuits for signal F As shown in Fig. 2, the sectionto the right of point D is occupied by the train W. Track relay F istherefore de-energized. All circuits for Winding 8 of line relay H areopen at front contact 24 of track relay F and relay H is thereforeenergized in the reverse direction. The stop indication circuit forsignal J is closed at back contact 33 of track relay F, and signal Jtherefore indicates stop.

Section CD is unoccupied, and track relay F is therefore energized. Allcircuits for winding 8 of line relay H are open at front contact 26 oftrack relay F, and relay H is therefore energized. in the reversedirection. The approach restricting indication circuit for signal J istherefore closed, and signal J C indicates approach restricting.

Section B-C is unoccupied, and track relay F is energized. The secondcircuit for Winding 8 of line relay H is closed over reverse contact 15of relay H and front con tact 26 of relay F and this relay is thereforeenergized in its middle direction. The approach indication circuit forsignal J is therefore closed, and signal J B indicates approach.

Section AB is unoccupied, and track relay F is energized. The thirdcircuit for winding 8 of line relay H is closed over middle contact 15of relay H and front contact 26 of relay F and line relay H is thereforeenergized in its normal direction. The proceed indication circuit forsignal J is therefore closed, and signal J indicates proceed.

One advantage of supplying the energy for the approach and proceedindications for each signal from the line transformer for the sectionnext in advance of the signal in the manner previously described, isthat if the line relay associated with the signal should fail to becomeenergized in the reverse direction for any reason, when the section nextin advance is occupied, the signal would become dark and the failure ofthe line relay would be detected. For example, if line relay I-I shouldfail to become energized in the reverse direction when the section tothe right of point D is occupied by a train as shown in the drawing, aswould be the case if winding 7 of this relay became open-circuited forany reason, all indication circuits for signal J would then be open, andsignal J would be dark. The improper operation of relay H wouldtherefore readily be detected.

It will be noted that the proceed indication circuit for each signalincludes a resistor 51. The electro-motive force supplied to the proceedindication circuit for each signal is greater than that supplied to theother indication circuits for each signal, and the normal function ofthe resistor 51 is to prevent the electromotive force impressed acrossthe lamps in the proceed indication circuit from exceeding the value ofthe electromotive force impressed across the lamps in the otherindication circuits. The resistor 51, however, also prevents theassociated signal from displaying a false proceed indication as would bethe case under some conditions of operation it the resistor 51 were notprovided. For example, if winding 7 of line relay H should be comeopen-circuited with the apparatus in the condition in which it is shownin the drawing, relay H would then become falsely energized in thenormal direction by the current in winding 8, and the contacts of relayH would occupy their normal positions, instead of their middlepositions. Under these conditions, if resistor 51 were not provided,signal J would indicate proceed instead of approach restricting. Sinceresistor 51 is included in this circuit, however, the electromotiveforce impressed across the lamps comprising the pr ceed indication forsignal J is not sufficient to light the lamps above a dull glow so thatsignal J will not display a normal proceed indication, and the failureof relay H will be detected.

Although I have herein shown and described only two forms of railwaytraffic controlling apparatus embodying my invention, it is understoodthat Various changes and modifications may be made therein within thescope of the appended claims without departing from the spirit and scopeof my invention.

Having thus described my invention, what I claim is:

1. In combination, a stretch of railway track, a line relay for saidstretch comprising three windings, means for constantly supplying two ofsaid windings with current, means controlled by traffic conditions insaid stretch for supplying the remaining winding with current, meanscontrolled by traffic conditions in advance of said stretch for at timesvarying the strength of the current supplied to said remaining winding,and governing means controlled by said relay.

2. In combination, a stretch of railway track, a track relay for saidstretch responsive to trafiic conditions in said stretch, a line relayfor said stretch comprising three windings, means for separatelysupplying two of said windings with current, means controlled by saidtrack relay for at times supplying said remaining winding with current,means controlled by traffic conditions in advance of said stretch forvarying the strength of the current supplied to said remaining winding,and traffic governing means controlled by said track relay and said linerelay.

In combination, a stretch of railway track; a relay for said stretchcomprising a first, a second, and a third winding; means for constantlysupplying said first and second windings with current, means for attimes supplying said third winding with current which neutralizes theeffect of the current in said second winding, means for at other timessupplying said third winding with current which opposes and exceeds theeffect of current in said second winding, and governing means controlledin part by said relay. 7

it. In combination, a stretch of railway track divided into tracksections, a relay for each track section having a local winding, areverse control winding, and a normal control winding, means forconstantly supplying the local winding and the reverse control windingof each relay with alternating cur rent, means effective when theassociated track section and the section next in advance are unoccupiedfor supplying the normal control winding of each relay with alternatingcurrent which neutralizes the effect of the alternating current in thercverse'control winding, means effective when the associated section andthe two sections next in advance are unoccupied for supplying the normalcontrol winding of each relay with alternating current which opposes andexceeds the effect of current in the reverse control winding; and arailway signal for each section controlled in part by the associatedrelay and arranged to indicate stop, approach, approach restricting, orproceed, depending upon traffic conditions in advance.

5. In combination, a stretch of railway track, a track relay for saidstretch, a line relay for said stretch comprising a first, a second, anda third winding; means for con stantly supplying said first and secondwindings with current, means controlled by a front contact of said trackrelay for at times supplying said third winding with current whichneutralizes the effect of current in said second winding, means alsocontrolled by a front contact of said track relay for at other timessupplying said third winding with current which opposes and exceeds theeffect of current in said second winding, and a railway signalcontrolled by said track relay and said line relay.

6. In combination, a stretch of railway track, a track relay for saidstretch, a line relay for said stretch comprising a first, a second, anda third winding, means for constantly supplying saidfirst and secondwindngs with current, means controlled by a front contact of said trackrelay for at times supplying said third winding with current whichneutralizes the effect of current in said second winding, means alsocontrolled by a front contact of said track relay for at other timessupplying said third winding with current which opposes and exceeds theeffect of current in said second winding; and a railway signalcontrolled by said track relay and said line relay in such manner thatsaid signal indicates stop when said track relay is de-energized butthat said signal indicates approach,

approach restricting, or proceed when said track relay is energizeddepending upon whether said third winding is tie-energized, suppliedwith current which opposes the effect of current in said second winding,or supplied with current which opposes and exceeds the effect of currentin said second winding, respectively.

7. In combination, a stretch of railway track, a source of alternatingcurrent con nected with the rails of said stretch, a track relay havinga track winding connected with the rails of said stretch and alsoprovided with a local winding; a line relay for said stretch comprisinga first, a second, and a third winding, and provided with middle,normal, and reverse contacts; a circuit for the local winding of saidtrack relay controlled by a reverse contact of said line relay, a stickcircuit for said track relay including a front contact of the relay,means for constantly supplying the first and second windings of saidline relay with alternating current, means for at times supplying thethird winding of said line relay with current which neutralizes theeffect of the current in said second winding, means for atothertimessupplying the third winding of said line relay with current whichexceeds and opposes the effect of current in said second winding; arailway signal for said section capable of indicating stop, approach,approach restricting, or proceed; means controlled by a back contact ofsaid track relay for causing said signal to indicate stop, meanscontrolled by a front contact of said track relay and a reverse contactof said line relay for causing said signal to indicate approach, meanscontrolled by a front contact of said track relay and a middle contactof said line relay for causing said signal to indicate approachrestricting, and means controlled'by a front contact of said track relayand a normal contact of said line relay for causing said signal toindicate proceed.

8. In combination, a stretch of railway track divided into tracksections, a source of alternating current connected with the rails ofeach track section, a track relay for each track section having a trackwinding con nected with the rails and also having a local winding; aline relay for each section having a local winding, a reverse controlwinding, and a normal control winding, and provided with middle,reverse, and normal contacts controlled jointly by said windings; acircuit for the local winding of each track relay controlled by areverse contact of the associated line relay, a stickcircuit for eachtrack relay, means for constantly supplying the local winding and thereverse control winding of each. line relay with alternating current;means controlled by a front contact of the associated track relay, afront contact of the 7 track relay for the section neXtin advance,

and a reverse contact of the line relay for the section next in advancefor at times supplying the normal control winding of each line relaywith alternating current which neutralizes the effect of the current insaid re verse control winding; means controlled by a front contact ofthe associated track relay, a front contact of the track relay for thesection next in advance, and either a middle or normal contact of theline relay for the section next in advance for at other times supplyingthe normal control winding of each line relay with current which'opposesand exceeds the eifect of current in the reverse control winding; asignal for each track section capable of indicating stop, approach,approach restricting, or proceed; means controlled by a back contact ofeach track relay for causing the associated signal to indicate stop,means controlled by a front contact of each track relay and a reversecontact of the associated line relay for causing. the associated signalto indicate approach, means controlled by a front contact of each trackrelay and a middle contact of the associated line relay for causing theassociated signal to indicate approach restricting, and means controlledby a front contact of each trackrelay and a normal contact of theassociated line relay for causing the associated signal to indicateproceed. i

9. In combination, a stretch of railway track divided into tracksections, a source of alternating current connected with the rails ofeach track section, a track relay for each track section havinga trackwinding connected with the rails and also having a local winding; a

line relay for each track section having a local winding, a reversecontrol winding, and a normal control winding, and provided withreverse, middle, and normal contacts controlled jointly by saidwindings; means for constantly supplying the local winding and thereverse control winding of each line relay with alternating current,means con trolled by a front contact of the associated track relay and afront contact of the track relay for the section next in advance as wellas a reverse contact of the line relay for the section next in advancefor at times supplying the normal control winding of each line relaywith alternating current which naturalizes the effect of the alternatingcurrent in the reverse control winding; means control led by a frontcontact of the associated track relay, a front contact of the trackrelay for the section next in advance, and either a middle or a normalcontact of the line relay for the section next in advancefor at othertimes supplying the normal control winding of each line relay withalternating current which opposes and exceeds the effect of current inthe reverse control winding; means controlled by a reverse contact ofthe associated line relay for supplying the local winding of each trackrelay with alternating current, a stick circuit for the local winding ofeach track relay, a railway signal for each track section having anupper and a lower group of electric lamps; the upper group of each signal comprising a green lamp, a first and second yellow lamp, and a redlamp; the lower group in each signal comprising a green lamp and a redlamp; a stop indication circuit for each signal including the red lampof the upper group and the red lamp of the lower group as well as a backcontact of the associated track relay; an approach indication circuitfor each signal including the second yellow lamp of the upper group andthe red lamp of the lower group as well as a front contact of theassociated track relay and a reverse contact of the associated linerelay; an approach restricting indication circuit for each signalincluding the first yellow lamp of the upper group and the green lamp ofthe lower group as well as a front contact of the associated track relayand a middle contact of the associated line relay, and a proceedindication circuit for each signal including the green lamp of the uppergroup and the red lamp of the lower group as well as a front contact ofthe associated track re lay and a normal contact of the associated linerelay.

10. In combination, a stretch of railway track, a source of alternatingcurrent connected with the rails of said stretch, a track relay having atrack winding connected with the rails of said stretch, a line relay forsaid stretch comprising a first, a second, and a third winding, meansfor constantly sup plying said first and second windings withalternating current, means controlled by a front contact of said trackrelay for at times supplying said third winding with alternating currentwhich aids the effect of current in said second winding, means for atother times supplying said third'winding with alternating current whichneutralizes the effect of current in said second winding, means forsupplying said third winding at still other times with alternatingcurrent which opposes and exceeds the effect of current in said secondwinding, and governing means controlled by said line relay and saidtrack relay.

11. In combination, a stretch of railway track divided into tracksections. a source of alternating current connected with the rails ofeach track section, a track relay for each track section having a trackwinding connected with the rails and also having a local wind ing; aline relay for each track section having a local winding, a reversecontrol winding, and a normal control winding, and provided withreverse, middle, and normal contacts controlled jointly by the windingsof the line relay; means for constantly supplying the local winding andthe reverse control winding of each linerelay with alternating current;means controlled by a front contact of the associated track relay and aback contact of the track relay for the section next in advance forsupplying the normal control winding of each line relay at times withalternating current which aids the effect of current in the reversecontrol winding, means controlled by a front contact of the associatedtrack relay and a front contact of the track relay for the section nextin advance as well as a reverse contact of the line relay for thesection next in advance for supplying the normal control winding of eachline relay atother times with alternating current which neutralizes theeffect of the alternating current in the reverse control winding, meanscontrolled by a front contact of the associated track relay and a frontcontact of the track relay for the section next in advance as well aseither a middle or normal contact of the line relay for the section nextin advance for supplying the normal control winding of each line relayat still other times with alternating current which opposes and exceedsthe effect of current in the reverse control winding; means controlledby a reverse contact of each line relay for supplying the local windingof the associated track relay with alternating current, a stick circuitfor the local winding of each track relay, a railway signal for eachtrack section having an upper and a lower group of electrical lamps; theupper group of each signal comprising a green lamp, a first and secondyellow lamp, and a red lamp; the lower group in each signal comprising agreen lamp and a red lamp; a stop indication circuit for each signalincluding the red lamp of the up per group and the red lamp of the lowergroup as well as a back contact of the associated track relay; anapproach indication circuit for each signal including the second yellowlamp 'of the upper group and the red lamp of the lower group as well asa front contact of the associated track relay and a reverse con tact ofthe associated line relay; an approach restricting indication circuitfor each signal including the first yellow lamp of the upper group andthe green lamp of the lower group as well as a front contact of theassociated track relay and a middle contact of the associated linerelay, and a proceed indication circuit for each signal including thegreen lamp of the upper group and the red lamp of the lower group aswell as a front contact of the associated track relay and a normalcontact of the associated line relay.

12. In combination, a stretch of railway track divided into tracksections, a source of alternating current connected with the rails ofeach track section, a track relay for each track section having a trackwinding connec ed with the rails and also having a local winding; a linerelay for each track section having a local winding, a reverse controlwinding, and a normal control winding, and provided with reverse,middle, and normal contacts controlled jointly by the windings of theline relay; means for constantly supplying the local winding and thereverse control winding of each line relay with alternating current;means controlled by a front contact of the associated track relay and afront contact of the track relay for the section next in advance as wellas a reverse contact of the line relay for the section next in advancefor at times supplying the normal control winding of each line relaywith alternating current which neutralizes the effect of the alternatingcurrent in the reverse control winding; means controlled by a frontcontact of the associated track relay, a front contact of the trackrelay for the section next in advance, and either a middle or a normalcontact of the line relay for the section next in advance for at othertimes supplying the normal control winding of each line relay withalternating current which opposes and exceeds the effect of current inthe reverse control winding; means controlled by a re verse contact ofthe associated line relay for supplying the local winding of each trackrelay with alternating current, a stick circuit for the local winding ofeach track relay, a railway signal for each track section having anupper and a lower group of electric lamps; the upper group of eachsignal comprising a green lamp, a first and second yellow lamp, and ared lamp; the lower group in each signal comprising a green lamp and ared lamp; a stop indication circuit for each signal in cluding the redlamp of the upper group and the red lamp of the lower group as well as aback contact of the associated track relay, an approach indicationcircuit for each signal including the second yellow lamp of the uppergroup and the red lamp of the lower group as well as a front contact ofthe associated track relay and a reverse contact of the associated linerelay; an approach restricting indication circuit for each signalincluding the first yellowlamp of the upper group and the green lamp ofthe lower group as well as a front contact ofthe associated track relay,a middle contact of the associated line relay, a front contact of thetrack relay for the section next in advance. and a reverse contact ofthe line relay for the section next in advance; a proceed indicationcircuit for each signal including the green lamp of the upper group andthe red lamp of the lower group as well as a front cont-act of theassociated track relay, a normal contact of the associated line relay, afront contact of the track relay for the section next in advance, andeither a middle or a normal contact of the line relay for the sectionnext in advance.

In testimony whereof I aflix my signature.

HOWARD A. THOMPSON.

